Yes, It is illegal that they did not release the 0.9.9 source as it derives from a GPL version and binaries were released. I seriously doubt they managed to get all developers in on the switch and then forgot to take the license out of the installer and help file.
So, why hasn't anything been said? Things have been said. I forget the last time it was discussed, but I think the reason source was not released was due to a conflict and people just stopped asking. The bottom line is, people aren't bothering them most likely because of the work they've done for the emuscene.